The invention relates to an optical arrangement, in particular for use as a main beam splitter and/or beam combiner in a microscope, wherein one or more light beams can be coupled into the arrangement and at least one of the light beams that were coupled in can be coupled out again after having passed through the optical arrangement. Further, the invention relates to a respective method.
In the field of microscopy, in particular, confocal microscopy, it is often necessary to split or combine light beams or individual parts thereof, most frequently chromatic portions of its spectrum. Beam splitting is often implemented by dichroic filters. Dichroic filters are narrow-band, high precision chromatic filters that work under the principle of interference. In contrast to conventional filters, the non-passing portions of the spectrum of the coupled in light beam is not absorbed but reflected by the filter. This allows cutting out a portion of the spectrum from the light beam. Dichroic filters comprise the distinctive disadvantages that these have fixed spectral properties. If these should be changed, the filter has to be replaced.
Therefore, in practical applications, AOBS (Accusto Optical Beam Splitters) are known. An AOBS consist of a crystal that is subjected to an acoustic wave. Therefore, the light beams passing through the crystal are deflected differently depending on their wavelength. This allows to couple out very narrow-banded portions of the spectrum of the coupled in light beams. If an AOBS is used in the reverse direction, light beams can be combined. By changing the frequency of the acoustic wave the position of the cut out spectral portion can be influenced. This allows implementing a beam splitter that can be controlled within a narrow range. One disadvantage is that AOBSs are expensive. Moreover, the cut out spectral portion is very narrow (typically less than 2 nm). Broad spectral portions cannot be generated with an AOBS.